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When the heater fan will only run on the highest setting, this is most commonly due to a faulty Blower Motor Resistor. If the fuse was the problem, the blower motor would not respond at all. There is not a fuse that covers just speed 1-3. The resistor will be the problem here. The resistor is located under the passenger's side dash, mounted near the blower motor (click here for an image). Inspect the electrical connector and wire harness for any loose, broken or damaged wires. If the visual inspection checks ok, replace the Blower Motor Resistor. Unplug the electrical connector and remove the 2 mounting screws. Reverse procedure to install. If my answer has helped you, please help me by leaving a rating using the stars at the top of this page or accept the answer so I may be credited. If you cannot rate or do not see the rating stars, please let me know. You can ask follow-up questions after you rate.
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